<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <div id="app">
    {{fn}}
  </div>
  <script src="./vue.js"></script>
  <script>
    const app = new Vue({
      el: "#app",
      data: {
        msg: "内容"
      },
      computed: {
        /* fn () {
          return this.msg
        } */
        fn: {
          get () {
            return this.msg
          },
          set (value) {
            console.log('内容改变', value)
          }
        }
      }
    })
  
  </script>
</body>
</html>